Anesthetic agents (halothane, enflurane, ketamine and fluroxene) were administered to rats once plasma renin activity (PRA) had been determined. When stable anesthesia had been obtained, PRA was again measured. PRA did not increase with these anesthetic agents. A competitive inhibitor of angiotensin II was then infused and blood pressure fell 20 torr with halothane and enflurane but not with ketamine or fluroxene. Animals fed a low sodium diet for 5 - 7 days reacted differently. PRA was elevated and rose further with these anesthetic agents. The competitive inhibitor caused blood pressure to fall 30 torr in the awake and the anesthetized animals. Future work will examine the renin-angiotensin system in states where the resting PRA has been altered and in other hypertensive models. Measurements of sympathetic nervous system activity will also be done.